1. Field of the Invention
The present invention relates to oil filters and more particularly to an oil filter assembly for a Volkswagen flat four opposed cylinder air cooled engine.
2. Description of the Prior Art
Oil filters have been utilized on engines and particularly on automobile engines for a long period of time. On older design automobile engines initially manufactured without an oil filter, it was usually possible for the manufacturer to redesign the engine to adapt an oil filter to the engine crankcase at some convenient location proximate the oil pan. This modification allowed standard enclosed canister oil filters to be secured directly to the automobile engine for filtering the oil on all subsequently manufactured designs and modification of the original engine.
In some older engine designs, in which it is desirable to retrofit an oil filter to the engine with after-market accessories, it is sometimes possible to adapt an oil filter assembly to the existing internal oil flow system by external connections or to tap into the crankcase or engine oil pan and siphon off a portion of the oil flow and run it through the filter. It is, of course, preferable to employ the prior option and interpose the oil filter into the full flow of oil volume and filter all of the oil constantly as it circulates through the engine. However, it is usually difficult if not impossible to do so if the engine oil flow or circulation system was not originally designed to include an oil filter, and it is an especially difficult problem to try and filter the full oil flow and keep the oil filter external to the engine for easy removal and replacement. The less desirable option when adding an oil filter to an engine not designed to utilize one is the alternative in which a portion of the oil flow is tapped off and circulated through a filter. It is easier in this design alternative to mount the oil filter in a separate container mounted close to the engine and run the oil to and from the filter through oil lines or hoses.
As a result, most after-market modifications for supplying an engine oil filter are usually less than desirable because of the usual difficulty, or inability in most cases, to direct all of the oil flow through the filtering process. It is too difficult to place a filter directly in the engine oil circulation system if the engine has not been initially designed to employ such an oil filter. Thus, most after-market systems usually filter only a portion of the oil and hardly ever in the most desirable manner of directly filtering the oil being picked up from the oil pan by the oil pump pickup tube which delivers oil to the oil pump for pressurized delivery throughout the engine lubrication system.
The ubiquitous Volkswagen flat four opposed cylinder air cooled engine was designed back in the 1930s by Dr. Ferdinand Porsche. It did not have an oil filter designed into the system and its unique design has prevented the adaption of efficient oil filters to the engine. In fact, up through the latest models of the engine manufactured for installation in Volkswagen "Bugs," they still only utilized an oil screen surrounding the oil pump pickup tube in the engine oil pan because of the inability to design an oil filter into the system. It has long been desired to provide an oil filter for these engines but the unique compact design has frustrated almost all prior attempts at achieving this result, and all attempts at providing full flow filtering.